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kirill115 [55]
3 years ago
15

An emerald gemstone is an impure form of the mineral beryl, Be3Al2Si16O18. What is the percentage of silicon in the mineral?

Chemistry
1 answer:
solong [7]3 years ago
4 0

Answer:

b. 54.9%

Explanation:

An emerald gemstone has the formula Be₃Al₂Si₁₆O₁₈. We can find the mass of each element in 1 mole of Be₃Al₂Si₁₆O₁₈ by multiplying the molar mass of the element by its atomicity.

Be: 3 × 9.01 g = 27.03 g

Al: 2 × 26.98 g = 53.96 g

Si: 16 × 28.09 g = 449.4 g

O: 18 × 16.00 g = 288.0 g

Total mass = 818.4 g

The mass percentage of silicon is:

(449.4 g / 818.4 g) × 100% = 54.91%

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The vapor pressure of ethanol is 400. mmhg at 63.5°c. its molar heat of vaporization is 39.3 kj/mol. what is the vapor pressure
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